Dead wood is not only a whole ecosystem in itself, it is vital to the wider ecosystem too. In addition to being homes/ sanctuary and food for a whole myriad of organisms, the natural, ultimate destination for deadwood is the creation of soil which then nourishes the future heath of a woodland. Woodland soil, especially within an ancient woodland like Revesby is amazing stuff. If you think about how much growth it supports every year – the sheer volume of plant material and never with any fertiliser or pesticides from humans – just with a network of interconnected life.
I thought I would write about one of the more overlooked lifeforms in woodland the (long word alert) ‘Saproxylic’ invertebrates. Those which – you guessed it! – use dead wood. So yes a long word which means dead-wood invertebrates, pronounced Sap– ro (as in robot) – xy (as in Xylophone) lic (as in what you are forced to do with a toddler’s dripping ice cream).
For much of the year deadwood invertebrates are hidden away as larvae within dead wood. It can be quite specific which part of the wood they need and indeed which species of tree. Some are found only in damp rot points where a branch has been lost, some are in the underground roots – or the material which collects over decades or longer, in the base of a hollow tree. Usually these invertebrates rely on fungi and other micro-organisms to turn the wood into more digestible materials and they feed on these directly/ indirectly.
Many of these creatures need not only a very specific sort of deadwood but they also need flowers. While the larvae may be happy chomping away on fungi or wood, the adults require nectar for energy and egg production. Flowers must also be right by the wood or within woodland glades/ rides. In nature of course, dead trees don’t move very far and so many dead wood invertebrates have lost the ability to move long distances because they have never needed to. If flowers are located too far away they may be out of reach.
This time of year is an excellent time to spot many of the species involved as they settle on the frothy-white, dinner-plate of a hogweed flower – of course any flower is worth a look (especially bramble) if you are out on a walk but hogweed is often such a convenient height that it makes creatures quite obvious.
The first picture is of a black and yellow longhorn beetle. Longhorn beetles get their name from the over-long antennae they have on their heads and this species is no exception. The markings can be quite variable but usually the yellow is thew dominant colour. This one has the scientific name Rutpela Maculata’ which helps to distinguish it from other black and yellow species.
The second picture is a hoverfly known as the ‘Batman Hoverfly’. It’s scientific name is ‘Myathropa Florea’ which although fun to say is a bit of a mouthful. So because the marking between the wing joints often resemble a batman symbol (if you squint) it was decided this was a nice catchy name. They are a big and striking hoverfly which appear quite fuzzy especially when fresh and they are often mistaken for a bee but they have very short antennae and only one pair of wings.
By Gillian Fisher, Ecologist.
